ms1 = 300 g , c1% = 8%
ms2 = 500 g , c2% = 20%
stim ca c% = mdx100/ms
=> md1 = ms1xc1/100
= 300x8/100 = 24 g
=> md2 = ms2xc2/100
= 500x20/100 = 100 g
=> md.tot = md1+md2 = 124 g
ms.tot = ms1+ms2 = 800 g
c%.final = md.totx100/ms.tot
= 124x100/800 = 15,5%